This invention relates to an oven for treating web stock or flat stock, especially wood, metal or pressed board coated with adhesive, glue, protective coatings or the like containing a high concentration of solvents, by means of special gaseous combustion and recycling.
In the typical treatment of various coated products and in the laminating manufacture of multiple layered products, a continuous product or lamination is passed through a conveyorized oven or heated chamber for solvent removal with drying. Heated gases are forced over the product in substantial volumes for evaporation of the solvent. During this process, the temperature of the gases is limited to a prescribed maximum for safety reasons, and to avoid damage to the coating or substrate. Consequently, it is typically necessary to have several heater sections in series to achieve effective drying. Such equipment requires substantial capital outlay, space and heat input. A great share of the generated heat is exhausted into the atmosphere and lost within the volumes of gases discharged. These gases are laden with varying and often excessive amounts of organic solvents driven off the product in the pre-dry, flash-off or first zone of the oven. These solvents are carried by means of the oven exhaust systems into the atmosphere. This of course is not ecologically desirable. It is recognized in the trade that present drying equipment, though effective, is expensive and space consuming to the user while the public in general is encumbered with higher fuel costs and finished product cost due to the tremendous quantities of fuel necessary to operate. The public also has the ecological disadvantage of undesirable stack discharge.